Introduction & Discovery

Blechnum novae-zelandiae, the New Zealand Kiokio, is the signature large chain fern of New Zealand's maritime temperate landscape and one of the most recognisable native plants of the country's rural countryside. Dense colonies of arching once-pinnate fronds a metre or more long line virtually every damp roadside cut, drainage ditch, and stream bank across both main islands, producing a distinctive vegetative pattern so consistent that New Zealanders often use the plant's presence as an unconscious signal of rural road travel. The species was first formally described by Gustav Heynhold in 1846 from material collected in New Zealand by early European botanists, though pre-Linnaean and early colonial collectors including Joseph Banks and Daniel Solander on Cook's first voyage had encountered the plant and similar large Blechnum species during their 1769 to 1770 visit. Recent molecular phylogenetic work by Thais Gasper, Alexandre Salino, and collaborators (2016 and 2017) has placed this species in the segregate genus Parablechnum, reflecting a comprehensive reassessment of the broadly defined Blechnum of earlier authors into multiple natural generic groupings; the Linnaean-form combination Blechnum novae-zelandiae is nonetheless retained in most horticultural and popular usage. Ecologically the species occupies a distinctive niche as a plant of saturated soils and flowing water margins, tolerant of levels of waterlogging that most terrestrial ferns cannot endure. Dense stands along stream banks and in wet swales stabilise the substrate against erosion and provide habitat for native invertebrates and ground-dwelling birds. The Maori name kiokio refers both to this species and to related large New Zealand Blechnum, and the young unfurling croziers were historically consumed as a cooked vegetable known as pikopiko, which remains a minor component of contemporary Maori cuisine and traditional kai. The fronds have also been used for thatching, bedding, and insulation in traditional Maori practice. In cultivation the species has become a popular garden fern in maritime temperate climates worldwide since the 1990s, valued for its bold architectural presence, spectacular pink new growth, tolerance of wet and shaded sites that defeat many other ferns, and relatively modest demands once a cool humid site is provided. It is among the most successful New Zealand plants in European maritime garden horticulture and offers a dramatic reminder of the evolutionary theatre of the Blechnaceae in the Southern Hemisphere.

Discovery & Naming

The New Zealand Kiokio was first formally described by the German botanist Gustav Heynhold in 1846, in his Nomenclator Botanicus Hortensis. Earlier European collectors including Joseph Banks and Daniel Solander on Cook's first voyage (1769 to 1770), and subsequently the Forsters on Cook's second voyage (1772 to 1775), had collected large New Zealand Blechnum material, but the confused taxonomy of the complex and the unsettled state of Southern Hemisphere fern systematics delayed its formal description by several decades. The species was subsequently treated by various nineteenth-century authors including William Colenso, Thomas Cheeseman, and various European pteridologists working on New Zealand material, and passed through a confused synonymy under various Blechnum and Lomaria combinations. The genus Blechnum itself was established by Linnaeus in 1753, while the segregate genus Lomaria was proposed by Willdenow in the early nineteenth century and applied widely to Southern Hemisphere large Blechnum species before falling out of favour. Throughout the twentieth century most New Zealand treatments placed the species in Blechnum, with detailed morphological and ecological study by Patrick Brownsey and John Smith-Dodsworth in the Field Guide to New Zealand Ferns and Lycophytes and in the online Flora of New Zealand. The comprehensive molecular phylogenetic work of Thais Gasper, Alexandre Salino, Eric Schuettpelz, and collaborators (2016 and 2017), which rearranged Blechnum sensu lato into multiple segregate genera based on molecular evidence, has placed this species in Parablechnum, and the combination Parablechnum novae-zelandiae is now used by some authors while the Linnaean-form Blechnum novae-zelandiae remains standard in horticultural and popular usage. The Maori knowledge of the plant under the name kiokio greatly predates European botanical description and represents a significant indigenous ethnobotanical record.

Native Range & Distribution Map

Distribution map showing the native range of Blechnum novae-zelandiae.

Biology & Frond Morphology

Blechnum novae-zelandiae belongs to the genus Blechnum in the family Blechnaceae, producing evergreen to semi-evergreen, essentially monomorphic, once-pinnate fronds of substantial size arising from a stout short-creeping to erect rhizome, commonly 70 to 150 centimetres long and in exceptional specimens reaching 200 centimetres in optimal conditions. blades are narrowly lanceolate to lanceolate-ovate, firm-papery to subcoriaceous in texture, and deep glossy green when mature, with new croziers emerging a vivid pink to bronze-red from anthocyanin pigments before darkening to bronze and then mature green over several weeks. pinnae are linear-lanceolate, 30 to 80 pairs per frond, gradually tapering to an acuminate apex, with entire to finely serrulate margins and a sessile to shortly stalked base. the lowermost pinnae are progressively reduced and deflexed. stipes are stout, dark brown to chestnut at the base, clothed with brown linear-lanceolate scales. fronds that unfurl from coiled fiddleheads (croziers). Like all ferns, it reproduces via spores borne on the underside of fertile fronds rather than flowers and seeds, and its life cycle alternates between a dominant sporophyte (the visible plant) and a small, short-lived gametophyte stage.

Reproduction & Propagation

Propagation of Blechnum novae-zelandiae can be achieved through several methods:

• Spores: Collect ripe spores from the underside of fertile fronds, sow on sterilised peat or peat/perlite mix. Do not cover. Keep humid and in bright indirect light. Prothalli (gametophytes) typically develop in 4–12 weeks, and young sporophytes appear after a further 2–6 months.
• Division: Mature clumps with multiple crowns or creeping rhizomes can be divided in spring as new fronds emerge.
• Rhizome cuttings / offsets: Epiphytic genera (Davallia, Polypodium, Phlebodium) can be propagated from 5–10 cm rhizome segments with at least one frond and visible roots.

Cultivation & Substrate

Successful cultivation of Blechnum novae-zelandiae depends on matching three conditions to its natural habitat: consistent moisture without waterlogging, a humus-rich yet well-drained substrate, and the correct light level for its frond type — whether dappled woodland shade, bright filtered light, or, for a handful of rock ferns, direct sun.

Common Mistakes to Avoid

Several recurring errors undermine cultivation of Blechnum novae-zelandiae outside New Zealand. Planting in hot dry inland continental climates produces chronically stressed plants that struggle to establish; the species demands cool humid maritime conditions and performs poorly where summer temperatures routinely exceed 28 degrees Celsius with low humidity. Inadequate summer irrigation in Mediterranean-climate gardens causes marginal browning, reduced frond size, and progressive decline; the species is among the most water-demanding of hardy ferns and requires deep weekly irrigation through dry summers. Planting in alkaline soil without amendment causes chlorosis and stunted growth; the species is a calcifuge and requires acidic substrate. Siting in full exposed sun outside New Zealand's uniquely humid maritime climate causes frond scorch and premature senescence; partial shade is essential away from its native range. Burying the crown by planting too deep or piling mulch over the rhizome invites rot. Expecting year-round evergreen performance in zones 7 and colder is unrealistic; winter foliage loss is normal in these climates and the plant regrows in spring. Spacing plants too closely leads to crowding within three to five years owing to the species' colonial habit. Confusing the species with related New Zealand Blechnum is common and identification requires attention to pinna shape, frond outline, and habitat.

Seasonal Considerations

Spring (September to November in the Southern Hemisphere, March to May in the Northern) is the main growth flush, with new croziers emerging vigorously from rhizome crowns and unfurling over three to five weeks with the characteristic pink colour. Remove any winter-damaged fronds before new growth starts, apply a spring topdressing of compost or balanced slow-release fertiliser, and renew mulch to 5 to 8 centimetres. Divide established clumps early in the season if division is planned for the year. Summer (December to February in the Southern Hemisphere) is the peak growth and ornamental period; maintain deep weekly irrigation in dry weather, keep mulch topped up, and monitor for slug damage to any late emerging fronds. Autumn brings a secondary growth flush in cool maritime climates as moisture returns and temperatures moderate; continue irrigation until winter rainfall arrives. Winter requires moderate attention in maritime zones 9 and 10, where the species is essentially evergreen with only cosmetic damage; in colder zones (7 and 8) apply heavy mulch over crowns and accept that foliage will be lost to frost and regrow in spring. Avoid heavy foot traffic around the crown at any season to prevent compaction of the rhizome system.

Diseases & Pests

Common issues affecting Blechnum novae-zelandiae in cultivation:

• Root/rhizome rot: Caused by waterlogged substrate, compacted soil, or overwatering in cool weather. Ensure the growing medium is well-aerated and never let pots sit in standing water for prolonged periods.
• Fungal leaf spot & Botrytis: Brown or grey blotches appear in stagnant, overly humid conditions. Improve air circulation, remove affected fronds, and avoid wetting foliage late in the day.
• Scale insects & mealybugs: The most common fern pests, hiding on stipes and frond undersides. Wipe off with a cotton swab dipped in diluted isopropyl alcohol, or treat with horticultural soap. Many chemical pesticides scorch fern fronds — always test on one frond first.
• Spider mites: Fine webbing and stippled fronds, common in dry indoor air. Raise humidity and rinse fronds regularly with tepid water.
• Frond browning (tip burn): Caused by dry air, direct hot sun, fluoridated or chlorinated tap water (especially in Nephrolepis, Calathea-loving filmy ferns), or soluble-salt build-up from fertiliser. Flush the pot with rainwater and reduce feeding.

Indoor Growing & Terrariums

Blechnum novae-zelandiae can be grown indoors as a houseplant or terrarium subject when its humidity and light requirements are met.

Indoor Setup

• Light: Bright indirect light — an east- or north-facing window, or 30–60 cm under an LED grow light (10–12 hours/day). Most ferns scorch in direct midday sun.
• Humidity: 50–80%. Group plants, stand pots on a pebble-and-water tray, or run a humidifier; misting alone rarely raises ambient humidity enough.
• Temperature: 16–24°C (60–75°F) for most indoor species; avoid cold drafts and hot radiators.
• Substrate: Peat-free potting mix with added perlite and orchid bark for drainage; epiphytic genera (Platycerium, Davallia) grow best mounted on bark or in a bark-heavy orchid mix.
• Water: Keep consistently moist but never waterlogged. Let the top 1–2 cm of substrate dry slightly between waterings in winter.
• Air circulation: A gentle fan discourages fungal leaf spot without drying out the fronds.

Landscape & Garden Use

Blechnum novae-zelandiae can be used in the garden wherever its hardiness and habitat preferences are matched. Ferns are classic choices for shaded borders, woodland gardens, stumperies, rockeries, stream-side plantings, and ground-cover under trees.

Landscape Tips

• Companions: Hostas, Astilbe, Heuchera, Tiarella, Epimedium, hellebores, snowdrops and other shade-tolerant perennials are classic partners.
• Soil preparation: Incorporate leaf mould or composted bark to improve moisture retention and mimic a forest floor.
• Mulching: A 3–5 cm mulch of chipped bark or leaf litter protects the rhizomes, conserves moisture, and slowly releases nutrients.
• Watering: Establish new plantings with regular deep watering during the first growing season; most hardy ferns need only occasional supplemental irrigation once established.

Conservation & Collector Notes

Blechnum novae-zelandiae is abundant throughout New Zealand and is assessed as Not Threatened under the New Zealand Threat Classification System. It is arguably the most abundant large chain fern in the country and has actually benefited from European agricultural development, which has created extensive suitable habitat along drainage ditches, roadside cuts, and cleared forest margins. The species is not listed on any international threat register. In its native New Zealand it is regarded as a valuable component of native vegetation and an important element of ecological restoration projects, particularly for wetland and stream margin revegetation. The plant is not in commercial trade from wild-collected material; nursery supply is entirely from spore-raised or divided stock. In New Zealand the species is a common component of commercial native plant nursery catalogues and is widely planted in restoration and amenity landscape work. Overseas the plant has been steadily introduced to European and North American horticulture since the 1980s, with increasing availability from specialist fern nurseries in the UK, continental Europe, and the Pacific Northwest. There is no evidence of invasiveness outside the native range despite occasional escapes from cultivation in mild maritime climates.

Collector Notes

For collectors building a Blechnaceae collection, B. novae-zelandiae is a signature Southern Hemisphere species and an essential representative of the New Zealand fern flora. Wild-provenance material from specific localities across New Zealand represents ecologically distinct stocks worth documenting; North Island lowland populations from the Waikato and Bay of Plenty, South Island populations from Westland and Fiordland, Chatham Islands populations, and sub-alpine populations from Mount Taranaki and the central North Island volcanic plateau all represent biologically distinct lineages. Some slight garden forms with variations in frond width, pinna shape, and new-growth colour have been noted but no formal cultivars are widely recognised, and the species is grown essentially in its wild form. Nursery stock in New Zealand is widely available from native plant specialist nurseries for restoration and amenity use. In the UK and continental Europe the species is offered by specialist fern nurseries including Fibrex Nurseries, Long Acre Plants, and a handful of continental European suppliers. In North America it is less widely distributed but increasingly available from Pacific Northwest fern specialists. Spore is exchanged through the American Fern Society and British Pteridological Society spore exchanges. Notable mature specimens in accessible collections include plantings at Logan Botanic Garden, Trebah Garden, Tregrehan Garden, Hillier Gardens, and at several New Zealand botanical institutions.

Ethnobotany & Cultural Significance

The Maori name kiokio applies collectively to this species and to several related large New Zealand Blechnum (now variously placed in Parablechnum and Austroblechnum), and the plant has a significant place in traditional Maori ethnobotany. Young unfurling croziers of kiokio were historically collected as a cooked vegetable known as pikopiko, prepared by boiling or steaming to neutralise bitter tannins and thiaminase and consumed as part of the traditional kai diet. The practice continues among some contemporary Maori communities as a minor component of native food use, and young croziers of kiokio appear occasionally on New Zealand restaurant menus featuring indigenous ingredients. The dried mature fronds have been used for thatching, bedding, insulation within whare (traditional houses), and as a crude filling material in various applications. The species' presence was noted as an indicator of freshwater seepage and subsurface moisture, useful information for locating springs and for evaluating land suitability. The rhizome has been used in some traditional rongoa (Maori medicine) applications, though specific uses are less well documented than for other New Zealand medicinal plants. European settlers from the nineteenth century onward generally ignored the species as ornamental or utilitarian, regarding it as an abundant roadside weed; its rehabilitation as a valued garden plant in international horticulture dates to the late twentieth century and the growth of specialist fern collecting and native New Zealand plant use.

Frequently Asked Questions